STS-135 Experiments and Test Objectives

Detailed Test Objectives

DTO 701-A - TriDAR

TriDAR is a relative navigation vision system that was developed by Neptec Design Group and funded by NASA and the Canadian Space Agency. The system provides guidance data that can be used for rendezvous and docking operations in space. The core elements of TriDAR are a laser based 3D sensor and a thermal imager. These instruments are used to gather information necessary to safely dock two spacecraft. The computer software uses the 3D image to match it against the known shape of the object that has been programmed into the computer to calculate its position and orientation. The biggest advantage of TriDAR is that it does not rely on tracking sensors that are mounted on the targeted vehicle. The Space Shuttle’s TCS (Trajectory Control System) needs reflective targets to gain information about it’s relative position. TriDAR is composed of a hybrid 3D camera that combines auto-synchronous laser triangulation technology with laser radar (LIDAR) in a single package allowing it to operate at both short and long range. The system can pick up targets at a range of about 3 kilometers. A thermal imager is also a part of TriDAR. That device is used to increase the range of the system beyond the LIDAR’s optical range. TriDAR can be used for several applications. It can be used for rendezvous and docking, planetary landings, vehicle inspection and navigation of unmanned rovers. TriDAR could also be used to provide 3D images during planetary rover missions. TriDAR can be used on earth to operate automated vehicles and a variety of other operations on earth. TriDAR flew for the first time on STS-128 and gathered data during Rendezvous and Docking as well Undocking and Flyaround. STS-131 also carried the unit. STS-135 will also fly the TriDAR unit designated DTO-701A (Detailed Test Objective). The Sensor is installed on the exterior airlock truss next to a Trajectory Control System Sensor. On STS-135, TriDAR will also be used to demonstrate technology for autonomous rendezvous and docking in orbit. The crew will have a laptop set up to display the information that is acquired by the system, however it will not be used to provide information to the Shuttle’s TCS. The hardware was installed in Atlantis’ Payload Bay on April 6, 2011. The TriDAR Sensor Package has a mass of 63lbs.

DTO 805 - Crosswind Landing Performance (DTO of Opportunity)

The purpose of this objective is to demonstrate the capability to perform a manually controlled landing in crosswind conditions. For that experiment, the Shuttle has to land on a runway that is outfitted with Microwave Scanning Beam Landing System Support to collect proper data. And a 90-degree crosswind of 10 to 15 knots has to be present.

Detailed Supplementary Objectives

DSO 640 - Physiological Factors

To determine physiological changes that occur when Astronauts are exposed to microgravity, pre- and post-flight tests are being conducted with the Astronauts. Those tests are called Functional Task Tests. This DSO will identify which physiological systems contribute to impaired performance in each of the tests. A goal of the study is to identify the physiological systems that play the largest roles in decrements in overall performance and to ultimately develop countermeasures. The crew of STS-135 will participate in pre-flight testing as well as testing just after landing.

A very significant physiological aspect of spaceflight that negatively impacts the flight crew is post-flight orthostatic intolerance. Individuals with orthostatic intolerance suffer from a abnormal systolic blood pressure during head-up tilt, elevated heart rates and presyncope or syncope with upright posture. This condition adds risk to re-entry and post-landing procedures, especially contingency operations. Current Shuttle Mission use fluid loading and Anti-G-Suits to mitigate the effects of this phenomenon. These countermeasures are not effective for all phases of re-entry and post-landing, that is why continous countermeasure development is important. Compression garments are being evaluated as countermeasures to provide a continous, graded compression from foot to hip and a static compression over the lower abdomen resulting in a more stable blood pressure. These garments will be easier to don and provide a better fit than currently used suits. Tests will be conducted before and after exposure to the microgravity environment to evaluate these garments.

Short Duration BioAstronautics Investigations

Sleep-Wake Actigraphy and Light Exposure during SpaceflightThis experiment will use ambulatory technology to monitor sleep-wake activity and light exposure patterns during the spaceflight. The data will provide a better understanding of the effects that spaceflight has on sleep and it will lead to countermeasures that will be used in future long and short duration missions. During STS-135 Mission Specialist Rex Walheim will participate in this experiment. He will have to complete a sleep log during the mission and he will wear an actiwatch that records sleep-wake activity for the entire mission.